Inertia starter



May 15, 1951 s. GILBERT 2,553,136

INERTIA STARTER Filed Jan. 24, 1949 2 Sheets-Sheet 1 INVENTOR. SAMUEL G/L BERT May 15, 1951 s. GILBERT 8 INERTIA s'rm'rsa Filed Jan. 24, 1949 g S t we gs-Sheet 2 IN V EN TOR.

SAMUEL G/LBE/QT Patented May '15, 1951 [TED STATES PT :25.

r orrlce INERTIA STARTER Application January 24, 1949, Serial No. 72,395

The present invention relates to starters and more particularly to the type of starter wherein a flywheel is energized to a high speed of rotation and then engaged to the engine to be started to crank it.

In starters of this type, it has long been recognized that it is highly desirable that the driving output member of the starter and the driven member of the engine, usually a pair of mating jaws, be engaged prior to the engagement of the rotating flywheel to the starter output member. Various means and methods for engaging the starter and engine jaws prior to the engagement of the flywheel have been proposed but most of the proposed means and methods have had various drawbacks, the most serious of which being rotation and transmittal of torque by the starter jaw element at the instant of engagement with the engine jaw element and the complicated expensive and bulky construction of such prior art starters in general.

[in object of the present invention is to provide improved engine starter of the inertia type which is of simple construction and effective operation.

Another object of the present invention is to provide novel means for causing the engagement of the starter jaw with the engine jaw prior to the operative engagement of the inertia member to the starter jaw in an inertia type starter.

Still another object of the present invention is to provide novel means in an inertia type starter whereby the starter jaw element is advanced into engagement with the engine jaw at element zero speed zero torque.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example.

in the drawings, Figure 1 shows a view partly in elevation and partly in section of a starter embodying the novel means of the present invention.

Figure 2 shows a cross-sectional view of Figure 1 along the line 2-2.

Referring now to the drawings wherein like reference characters indicate like parts in the two figures, there is shown in Figure 1, an inertia starter enclosed housing it comprising a jaw advancing mechanism housing portion i2, gear housing portion it, and motor housing portion it held together in any convenient manner such as by studs and nuts as shown. The construction 6 Claims. (Cl. 123-479) of the jaw advancing mechanism may be of the type described in the copending U. S. application Serial No. 673,069, filed May 29, 1946 entitled Engine Starter and the Like and assigned to the same assignee as the present application, or such jaw advancing mechanisms may be of a type well known in the art. Illustration and description thereof has been omitted in order to render a more clear presentation of the novel features of the present invntion. Such jaw advancing mechanisms comprise, in general, a rotating barrel i3 driven as from an. internal gear 18 and adapted to drive an axially stationary long-lead screw 15 through a preset torque limiting friction disc pack clutch H. The long-lead screw advances the jaw member i9 until a usual shoulder 2i on the jaw member abuts a usual corresponding shoulder 23 on the long-lead screw thus causing rotation of the jaw member by further rotation of the barrel. Internal gear l8 and driving pinion 20 are rotatively mounted on stub shafts 22 and 24 respectively, which are journaled in ball bearings supported in wall portion or partition 25 of clutch housing portion M. The other end of stud shaft 24 is journaled in bearing 28 supported in wall portion 36 secured to a shoulder 52 of clutch housing It as by screws 34, which wall portion also supports ball bearings 36 in which a hollow motor shaft 33 is journaled. The starter motor is indicated at 43. Motor shaft 38 supports and is keyed or splined to rotatable inertia member or flywheel 32. The flywheel may, of course, also be rotated by a hand crank unit or other means well known in the art. Motor shaft 33 is terminated in driving means such as a pinion it. The construction so far described is conventional and well known in the art and forms no part of the present invention. In the conventional inertia type starter pinion M is arranged to drive internal gear [8 either directly or through a reduction gearing and the Whole gear train is put into motion when the flywheel is brought up to speed. A spring loaded meshing rod is provided for keeping the starter jaw away from the engine jaw during the acceleration of the flywheel and when the flywheel has attained a predetermined operating speed, the meshing rod is actuated either manually or by means of a solenoid to engage the starter jaw with the engine jaw. In the novel starter of the present invention a jaw meshing rod is not used. Friction against the jaw element together with the action of the rotating axially stationary nut on the screw shaft connected to the jaw element, as explained in my aforementioned copending U. S.

application, will cause the starter jaw to advance and engage the engine jaw as soon as the flywheel is put in motion and complete engagement is usually accomplished within the first revolution of the flywheel. A suggestion has been advanced to provide means whereby the tension in the torque limiting friction disc pack of the jaw advancing mechanism released whereby just suificient friction remains in the disc pack to ad- Vance the jaw element but to slip after the starter jaw is engaged to the engine jaw and then to reapply the tension to the disc pack when the flywheel has attained operating speed. However, it is highly important that the tension of the torque limiting disc pack be accurately preset so as to provide ample torque for cranking the engine yet be able to protect the starter mechanism should the engine abnormally resist cranking or if it should backfire, throughout the life of the starter. The above-mentioned method of periodically releasing the tension of the disc pack would make such accurate presetting of the torque limiting value practically impossible.

In the present invention, means are provided for operatively connecting driving means 44 with internal gear is of the jaw advancing mechanism whereby sufficient torque is transmitted thereto from the driving means to operate the jaw advancing mechanism but insufficient to transmit appreciable torque thereto after engagement of the starter jaw with the engine jaw including means for increasing the torque transmitting capacity of said connecting means to a value substantially higher than the torque limiting value of the disc pack of the jaw advancing.

mechanism.

In the particular embodiment shown in the drawings the connecting means between pinion 44 and internal gear 18 of the jaw advancing mechanism is shown as a disc type friction clutch generally indicated at 38 having friction discs 48 and 58 alternately internally splined to annular hub portion SI of ring gear 52 and externally to hub tit keyed to the stub shaft 24 as by key 56, respectively, but another type of clutch such as an internal expanding clutch or a cone type clutch in and of itself well known in the art may, of course, be found more suitable for certain applications.

In the disc type clutch shown for the sake of illustrating the principle of the present invention, the interleaved discs are backed by a ring member 58 held against flange 69 forming part of and extending inwardly from ring gear 52. Annular ring member 62 is internally splined to annular hub portion 5| so as to rotate therewith but axially slidable therein and is kept in position as by a snap ring E l in an annular groove. Annular ring member 66 has an axially extending hub portion 68 adapted to receive the inner race of ball bearing 5 whose outer race is securely mounted in ring member 52. Adapted to press axially against ring member 86 so as to urge discs 418 and 5 against each other is a lever 12 having a forked end M straddling shaft 2% and being pivotally mounted between end portions 15 of slotted protrusion 18 of wall portion 25 by means of a pin 79. The end of lever 12 opposite the forked end "I l has a flat surface 83 resting against an operating rod 32 extending through the hollow shaft 38 which rod when actuated will move surface 85 to the left as seen in the drawing thereby pressing discs 48 and 56 against the backing ring 58 through ring members 65 and 62 and bearing Hi thus in effect locking ring gear 52 to hub 54. Operating rod 82 may be operated by electromagnetic means such as a solenoid actuated by manually operated switch or by a centrifugal switch connected with the flywheel, manually, or by the use of a governor depending on the particular application to which the invention is placed.

In operation, the flywheel G2 is rotated, in this particular embodiment, by motor means 49. Operating rod 82 in its retracted position as shown exerts little or no force against lever 12. Although discs t8 and 50 are not pressed together, the inherent friction or drag between the interleaved discs will transmit sufiicient torque from pinion id to hub 54 to rotate shaft 25 thus actuating the jaw advancing mechanism until 'jaw I9 meshes with a mating engine jaw (not shown). As soon as meshing of the jaws occurs, the reaction will increase the load and cause the friction discs 48 and 5% to slip relative to each other. If it is found that friction discs fail to transmit suflicient torque to actuate the jaw advancing mechanism, it may be preloaded as by spring means forcing operating rod 82 to the left as viewed in the drawing. It is to be noted that in this arrangement, the starter jaw is advanced at substantially zero torque and zero rotational speed. When flywheel t2 attains operating speed, operating rod 82 is actuated towards the left. Forcing surface of lever 12 to the left will press forked end 14 against ring member 66 and thus force friction discs t8 and 5t against each other through bearing is and ring member 62 thus effectively locking ring gear 52 to hub 5 and permit flywheel pinion to crank the engine through pinion 2E and internal gear 33 of the jaw advancing mechanism. It should be noted that even if rod 82 were actuated by snap action, the clutch mechanism 46 will take most of the shock loading which otherwise would have to be absorbed by the starter gearing.

if the engine offers abnormal resistance to turning, or, if it backflres, the preset torque limiting disc pack is of the jaw advancing mechanism will slip and thus protect the operating parts of the starter against excessive and destructive loading. The friction clutch 56 should be designed so that it will have a substantially higher equivalent slip value in locked position than the torque limiting disc pack in order to insure proper operating and protection characteristics of the starter.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

In an engine starter the combination of a rotatable extendable driving member adapted to engage and drive a driven member of an engine to be cranked, a driving member advancing mechanism including preset torque limiting means, a flywheel, means for rotating said flywheel and storing energy therein, means including gearing for connecting said flywheel to said driving member, advancing meanscomprising a disc clutch normally released but having sumcient drag to operate saidadvancing mechanism to advance said driving member into engagement with said driven member but insufiicient to crank said engine when the flywheel is rotated, means including a pivoted member pressing discs together and actuated by an operating rod for increasing the slip value of said disc clutch to a value substantially higher than said torque limiting means thereby establishing driving connection, between said flywheel and said driven member when said flywheel has attained a predetermined rotative speed.

2. In an inertia starter comprising, in combination, a flywheel, means for actuating said flywheel, driving means driven by said flywheel, a clutch, an engine engaging jaw, a jaw advancing mechanism including torque limiting means, said clutch being operatively connected with said flywheel and said jaw advancing mechanism and having a drag in released position sumcient to cause said jaw advancing mechanism to bring said jaw into engagement with a jaw of the engine to be cranked upon initial rotation of said flywheel, and means including a lever member for increasing the drag on said clutch member upon said flywheel attaining a predetermined speed to operatively connect said flywheel to said driving means to crank said engine.

3. In an inertia starter having a rotatable inertia member and driving means therefor, an extendabie and rotatable jaw, and a jaw advancing mechanism including a preset torque limiting means; the combination comprising a clutch interposed between said rotatable inertia member and said jaw advancing mechanism having suflicient drag in released position to operate said jaw advancing mechanism to advance said jaw into engagement with a corresponding jaw of an engine to be started upon initial rotation of said inertia member and adapted to slip when said jaws engage, and means to adjust said clutch to a higher slip value to effect rotation of said engine jaw by said inertia member.

4. In an inertia starter having a rotatable inertia member and means for rotating said inertia member, an extendable rotatable jaw member adapted to engage a jaw of an engine to be cranked, means for advancing said jaw member including torque limiting means, means independent of said torque limiting means for transmitting sufiicient torque from said inertia member to said jaw advancing mechanism to advance said jaw member into engagement with the engine jaw but insuflicient to crank said engine upon initial rotation of said inertia member, and means for increasing the torque transmitting capacity of said transmitting means to a value sufllcient to crank said engine, said last value being substantially higher than said torque limiting means of said jaw advancing means.

5. A starter having a rotatable inertia member and means for rotating said member and storing energy therein, a rotatable extendable jaw element adapted to drivingly engage a mating jaw element of an engine to be started, the driving connection between said inertia member and said starter jaw comprising a jaw advancing mechanism, a preset torque limiting means, and a f iction clutch, said friction clutch having sufficient drag in released position to operate said jaw advancing mechanism to bring said jaws into engagement but insufficient to crank the engine upon initial rotation of said inertia member, and means for operating said friction clutch to effect a higher slip value than said torque limiting means, thereby completing the driving engagement to the engine to be started when said member has attained operating speed.

6. In an engine starter having a driving member, means for extending and driving said member, a flywheel, means for rotating said flywheel and storing energy therein, the combination of means for operatively connecting said flywheel to 5 id extending and driving means comprising a gear train, preset torque limiting means, and friction clutch means, said friction clutch means being normally in released position having sumcient frictional drag to extend but insufficient to drive said member upon initial rotation of said flywheel, and means for actuating said clutch upon said flywheel reaching a predetermined speed to have sufiicient frictional drag to drive said member and having a torque transmitting capacity substantially higher than the torque transmitting capacity of said torque limiting means.

SAMUEL GILBERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,752,835 Chilton Apr. 1, 1930 1,848,361 Lansing Mar. 8, 1932 2,038,182 Linder Apr. 21, 1936 

